Fig. 4

Phylogenetic relationships of reference methanogens and mcrA sequences retrieved from the digesters. The mcrA clone libraries were obtained from DNA samples collected on day 280, i.e. in period 3, from digesters D37, D^TE37, D42 and D^TE42. The relative abundances of the OTUs (99 % identity threshold) in the digesters are given in brackets and the GenBank accession numbers for representative sequences are specified at the end. Assemblages A, B and C are OTUs resembling with ≥97 % identity, and their closest relatives. The scale bar represents 10 % sequence divergence. Values at the nodes are the percentages of 1000 bootstrap replicates; values below 50 % are not shown